The invention disclosed relates to a splicer device for joining the trailing end of a used-up roll of strip with the leading end of a new roll.
The art field in question is that embracing packaging machinery, and in particular, machines such as are used for wrapping cigarettes.
Paper strip or thermoplastic film serving to envelop the product is purchased in rolls, often of considerable dimensions, and to avoid halting production whenever the roll of film or paper runs out, packaging machines of the type are generally provided with a device that carries two rolls; one of the rolls is used to supply a cutting device with strip material for packaging, the strip being severed into discrete lengths for infeed to the wrapping equipment, whilst the remaining roll provides a reserve supply, ready to be fed into the line once the first roll has run out.
In prior art packaging machines which make use of such materials, the replacement of the supply roll with a new roll is generally accomplished by splicing the trailing end of the strip wound off the supply roll, with the leading end of a new roll.
One method of producing a splice consists in inserting a length of tape, gummed on both sides, between the two overlapping strips, and pressing the three components firmly into contact in order to obtain a solid bond.
With the splice effected, one avoids any break in continuity of the supply of wrapping material to the packaging machine, since it is the selfsame trailing end of the strip wound off the old supply roll, now used up, that draws the leading end of the new roll of strip toward the cutting device.
A product which happens to be wrapped in the length of material comprising the splice will be discarded ultimately by the machine.
Such devices for splicing the ends of strip material nevertheless present certain drawbacks due to the fact that the area of the strips effectively bonded represents only a limited part of the actual stretch through which the material overlaps; as a result, the leading end of the new strip can fold over and stick when proceeding toward the work area, causing obstruction to the smooth passage of the material.
A second drawback arises in those instances where the cutting means which divide the strip into discrete lengths happen to effect the cut at a point in which the two strips overlap but are not bonded; this signifies that a sliver of the strip material will be separated totally and may fall onto the packaging line, occasioning a impediment to smooth operation of the machine.
The object of the invention is that of embodying a device for splicing strip in heat-sealable material, that will not give rise to the drawbacks described above.
The difficulty which the invention sets out to overcome is that of ensuring that the two spliced strips will be bonded together through their entire overlapping stretches; accordingly, there will be no loose flaps that can fold back, or become severed into slivers that fall onto the packaging line.